Shock wave trap for multiple combustion chamber reso-jet motors



Oct. 17, 1950 J. Y. DUNBAR suocx WAVE m? FOR MULTIPLE comausuon CHAIIBERRESO-JET MOTORS Filed Aug. 2, 1945 /v 1/51: I 1, :v, 11535:: A l

INVENTOR JAMES Y. DUNBAR nub-1x4.

L ATToRnQ! Patented Oct. 17, 1950 SHOCK WAVE TRAP FOR MULTIPLE COM-BUSTION CHAMBER RESO-J ET MOTORS James Y. Dunbar, United States NavyApplication August 2, 1945, Serial No. 608,543

6 Claims.

(01. fill-35.6)

(Granted under the act of March 3, 1883, as

This invention relates to improvements in resojet motors and isparticularly directed to the combustion chamber of said motors.

An object of this invention is to provide a reso- J'et motor that has anincreased eificiency.

Another object of this invention is to provide a reso-jet motor that hasa shock wave trap adapted to give an increased compression to the gasesin the combustion chambers of the said motor.

Other objects and advantages of this invention will become apparent asthe discussion proceeds and is considered in connection with theaccompanying claims and drawing wherein like characters of referencedesignate like parts through Fig. II is a sectional view of the shockwave trap embodied in this invention taken on the lines IIII of Fig. I;and

Fig. III is a sectional view taken on the line III-III of Fig. I.

Referring now to the drawing, wherein for the purpose of illustration isshown a preferred embodiment of this invention, the numerals 5 and Bdesignate combustion chambers of a dual resojet motor, having resonantexhaust tubes I and 8. The numeral 9 designates spark plugs provided inboth chambers which are used for the initial firing of these chambers.The subsequent charges in both chambers are fired from the flash-back inthe resonant exhaust tubes from the preceding charge in each of thechambers. The chambers 5 and 6 are provided with end coverings or platesIn and II, respectively. In each of the said end plates are providedair-inlet openings l2 and I3, positioned approximately as shown, andsmaller in cross sectional area than either exhaust tubes 1 or 8.

A shock wave trap chamber l4, formed by a case or housing I5 is afiixedin any suitable manner, such as by welding or the like, to the said endplates 10 and II. The chamber I4 includes, and permits openvcommunication between, both of the openings l2 and I3. It is to be notedthat due to the pressure under which the chamber 14 operates, theconnection between the housing I5 and the end plates I and I I must bepressuretight. An air-intake I6 is provided in and communicating withthe housing l5, as shown. It is to be further noted here that thestructure, shown for the purpose of illustration only, is a valvelesstyne reso-jet motor. A motor having valves of the vibrating orsynchronously-controlled meamended April 30, 1928; 370 O. G. 757) shown.The said baiile ll divides the chamber l4 into semi-chambers andpartially surrounds each of the openings 12 and I3. A bridge [8, formedby the baiiie IT, at its point of contact with the end plates Ill andII, forms a passage [9. Fuel for the chambers 5 and 6 enters openings 20and 2| through the said passage l9, which is supplied with fuel by anywell known means, such as the fuel'line 26. The passage [9 may beomitted from the structure, and fuel admitted to the chambers in anyconventional manner desired, without departing from the spirit of thisinvention.

In operation, the chambers 5 and B are phased to fire alternately. Thecharges in each of the chambers are initially exploded from the sparkplugs 9, and the resulting flame front from these explosions initiallyfires the subsequent charges. Expanding gases from the explosionoccurring in one chamber move outward through the exhaust tube or tailpipes I or 8 of each chamber and, likewise, simultaneously back throughthe openings [2 or l3, to divert the incoming air to the other chamber.Less gas, and consequently less pressure, will pass through the openingsI2 and I3 than through the tail pipes 1 and 8 because of the differencein cross-sectional area of the respective openings in the exhaust tubesand the openings, and further because of the internal surface contoursof chambers 5 and 6 and further again because of the difierence ofacoustical inertia between the tailpipe and the air intake IE. It is tobe here noted that no specific size for the openings and I3 isrecommended in this specification, because the size of the openings willvary according to the structural design of the motor. However, aspointed out above, these openings, l2 and I3, will always be less incrosssectional area than the tail pipes but each should beof the samesize as the air-inlet IS.

A high pressure wave front of gas, excited into motion as the result ofthe explosion in the chamber 5, moves out the exhaust tube '1 and theopening l2 into the shock wave trap chamber I4. is turned downwarddegrees by the concave corner to the rear of said trap. The impact, ofthe moving gas striking this corner dissipates the energy from the wavefront and translates it into forward thrust on the motor. The wave frontthen, under a lessened velocity, moves on downward past the intakepassage It, diverting all of the incoming air to the other chamber 6,which at this time is approaching the end of the low pressure phase 'ofits cycle, and is preparing to enter the compression phase of its cycle.As the incoming air from the passage 16 is diverted to the chamber 6,the pressure is increased by the remaining energy from the wave front,and is carried on into chamber 8 under this increased pressure, and actsas a resisting piston to the wave front returning from the resonantexhaust tube 8. The result is that the combined pressures, i. e., thepressure of the incoming air through the opening I3 and the pressurefrom the resonant wave front of the exhaust tube 8, gives a highercompression of air, in the chamber 8, Just prior to the explosion phaseof the cycle of this chamber than the air would have if the compressionwere from the resonant wave front alone. Consequently an increasedefllciency of the exploding fuel and air in this chamber will result. Asthe explosion occurs in chamber 6, the cycle is reversed and thefuel-air compression in chamber is increased.

It is to be understood that the form of this invention herein shown anddescribed isto be taken as a preferred example of the same, and

that various changes in shape, size and arrangement of parts may beresorted to without departing from the spirit of this invention or thescope of the apparent claims.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

l. A reso-iet motor comprising a combustion means having an air inletand discharge nozzle means in combination with a shock wave trapcommunicating with the said combustion means by two eccentricallylocated ports at one end and with the air inlet by a central port at theother, and having baflies for directing air from the air inlet and gasesfrom one of said eccentrically located ports into said othereccentrically located port.

2. A reso-jet motor comprising a plurality of combustion chambers phasedto fire alternately, and a shock wave trap communicating with the saidcombustion chambers solely at the intake ends thereof and having bafflesfor directing a portion of the explosion gases alternately from each oneof said chambers through said wave trap into the other chamber forraising the pressure therein at a time when said chamber has a returnwave from the previous explosion causing a compression of the chargetherein.

3. A reso-jet motor comprising combustion chambers each having anair-inlet opening, a housing forming a shock wave trap affixed to thesaid combustion chambers communicating with the said air-inlet openings,an air-inlet aillxed to the said housing, and a bailie within the saidhousing disposed between the air-inlet openings of the said combustionchambers for directing the air from said air inlet in the housing intosaid combustion chamber air-inlet openings.

4. A reso-jet motor comprising two combustion chambers phased to firealternately, airintake openings in the said chambers, and a shock wavetrap communicating with the said openings having an inlet for incomingair charges and baflle means cooperating with said wave trap to directgas from one chamber escaping through the corresponding air intakeopening during the combustion cycle to drive an incoming air charge intothe other chamber through its intake opening.

5. A reso-jet motor comprising cooperating combustion chambers phased tofire degrees apart, air-inlet openings provided in the said combustionchambers, an additional chamber communicating with all the saidair-inlet openings carrying air-inlet means, and a baffle in the saidadditional chamber, said baflie being so formed as to direct the passageof gas under pressure from one of the said combustion chambers duringexplosion passing through said air inlet means into another combustionchamber phased 180 therefrom creating a low pressure area at the saidair inlet means diverting air into said other combustion chamber andforcing the said airinto said other combustion chamber under pressurejust prior to the explosion of the charge in said other combustionchamber.

6'. A reso-jet motor comprising a pair of parallel combustion chambers,each having an air inlet port and a tail pipe, a housing forming a shockwave trap forwardly of and communicating with said air inlet ports, anair inlet affixed to the forward end of said housing, and a bafflewithin said housing disposed between the air inlet ports and directingthe air from said housing air inlet into said ports.

JAMES Y. DUNBAR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,801,007 Jezler Apr. 14, 19312,503,584 Lipkowski Apr. 11, 1950 FOREIGN PATENTS Number Country Date412,478 France May 3, 1910

